Nutrition experts recommend fish as a healthy protein source that’s packed with beneficial omega-3 fats. But environmental groups have warned for years about the health risks of mercury and other contaminants in fish, particularly for pregnant women.

Dariush Mozaffarian, associate professor in the Department of Epidemiology at Harvard School of Public Health, weighed in on the controversy in an April 2, 2012 article in The Washington Post. Mozaffarian served on a joint advisory panel for the Food and Agriculture Organization of the United Nations and the World Health Organization, which in 2010 advised that pregnant women limit their fish consumption to 12 ounces per week and avoid the four highest-mercury fish (swordfish, shark, tilefish, and king mackerel). Other people need not limit their intake, according to the panel, although those who eat more than two servings of fish weekly should vary the type of fish they consume.

“As long as you’re not a pregnant woman, the evidence suggests that the balance is always toward net benefit,” Mozaffarian told the Post.